Reactive polymer coatings were synthesized via chemical vapor deposition (CVD) polymerization process. These coatings decouple surface design from bulk properties of underlying materials and provide a facile and general route to support thiol-ene and thiol-yne reactions on a variety of substrate materials. Through the reported technique, surface functions can be activated through a simple design of thiol-terminated molecules such as polyethylene glycols (PEGs) or peptides (GRGDYC), and the according biological functions were demonstrated in controlled and low-fouling protein adsorptions as well as accurately manipulated cell attachments.
The vapor deposition of polymers on regular stationary substrates is widely known to form uniform thin films. Here we report porous polymer particles with sizes controllable down to the nanometer scale can be produced using a fabrication process based on chemical vapor deposition (CVD) on a dynamic substrate, i.e., sublimating ice particles. The results indicate that the vapor deposition of a polymer is directed by the sublimation process; instead of forming a thin film polymer, the deposited polymers replicated the size and shape of the ice particle. Defined size and porosity of the polymer particles are controllable with respect to varying the processing time. Extendable applications are shown to install multiple functional sites on the particles in one step and to localize metals/oxides forming composite particles. In addition, one fabrication cycle requires approximately 60 min to complete, and potential scaling up the production of the porous particles is manageable.
Chemical vapor deposition polymerization was used to deposit a novel maleimide-functionalized poly-p-xylylene coating on various substrates. The coated substrates are readily able to undergo thiol-maleimide click reaction under mild conditions. Applications using this coating technology are highlighted in low-protein-fouling modification as well as manipulated attachments and growth of bovine arterial endothelial cells.
Chemical or biological gradients that are composed of multifunctional and/or multidirectional guidance cues are of fundamental importance for prospective biomaterials and biointerfaces. As a proof of concept, a general modification approach for generating multifunctional and continuous gradients was realized via two controlled and reversed click reactions, namely, thermo-activated thiol-yne and copper-free alkyne and azide click reactions. The cell adhesion property of fibroblasts was guided in a gradient with an enhancement, showing that the PEG molecule and RGD peptide were countercurrently immobilized to form such reversed gradients (with negating of the cell adhesion property). Using the gradient modification protocol to also create countercurrent distributions of FGF-2 and BMP-2 gradients, the demonstration of not only multifunctional but also gradient biointerfacial properties was resolved in time latencies on one surface by showing the manipulation in gradients toward proliferation and osteogenic differentiation for adipose-derived stem cells.
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